Depending who you ask, the 2024 High Court decision of Kramer v Stone[1] has redefined the circumstances in which a court will intervene in relation to succession promises, or doesn’t change much at all.[2]
It remains the case that an asset-holder’s succession decisions are vulnerable to challenge where they are inconsistent with other promises made and relied on to a third party’s detriment. Kramer v Stone does however raise several important and as-yet undetermined questions, including whether:
Until a clear body of case law emerges, ideally across jurisdictions, this uncertainty presents an added challenge for advisors counselling clients on succession decisions and leaves more room for disputes.
Succession promises before Kramer v Stone
Previously, attempts to hold a party to non-contractual succession promises were frequently litigated as claims of proprietary estoppel by encouragement[3] or promissory estoppel:
Whilst both proprietary and promissory estoppel are species of equitable estoppel, they involve different characteristics.[4] The Waltons Stores[5] “common” elements of equitable estoppel are a “useful check”, but not something to be applied in a mechanical fashion and do not combine the species of equitable estoppel.[6]
A claim of proprietary estoppel held several attractive features:
In contrast, a claim of promissory estoppel involved several hurdles:
Succession promises regarding identifiable assets squarely fell within the ambit of proprietary estoppel (even if within a class or subject to fluctuation over time[12]), but it was less obvious if this was also the case for other types of succession promises, such as promises about a proportion of the asset-holder’s total assets (e.g., a share of an estate). Certainly, several recent decisions ran and died as promissory rather than proprietary estoppel claims[13] and in other instances claimants invoked both forms of estoppel and the relevant judgments did not decide the issue.[14]
The Kramer v Stone reformulation
Kramer v Stone was litigated by the parties and determined in the lower courts as a case of proprietary estoppel. Notwithstanding this, the High Court opted to refine the Waltons Stores elements to consider the claim through the lens of an “equitable estoppel arising by reason of encouragement from a promise”. The refined formulation requires:
Relief is to be moulded to prevent the detriment.[15] Where life-changing decisions are involved, the likely relief is fulfilment of the promise, but if the detriment is a relatively small and quantifiable monetary outlay, the likely relief will be compensation.[16]
Impact: certainty of the promise
Claims of promissory estoppel have long required a “clear and unequivocal” promise before a court may intervene. In contrast, prior to Kramer v Stone, various appellate authorities considered proprietary estoppel claims could be supported by a “sufficiently clear” promise,[17] a lower threshold.
Whilst this line of authority was not explicitly rejected in Kramer, most decisions post-dating it have accepted that the higher “clear and unequivocal” standard must be applied to claims involving property rights.[18]
To be “clear and unequivocal”, the promise must be precise and unambiguous;[19] that is, it must be able to be understood in a particular sense by the person to whom it is addressed,[20] to the extent necessary for the propounded meaning.[21] If necessary, the promise can be implied or adduced from failure to speak where there was a duty to do so, or from conduct.[22] It must also be capable of misleading a reasonable person in the way in which the claimant alleges they have been misled.[23] There are competing authorities as to whether a representation of contractual certainty is required.[24]
Impact: measure of relief
As set out above, most recent authorities prior to Kramer v Stone considered that fulfilment of the promise was the starting point in crafting relief. In its wake, whilst the same approach has continued to be applied by some courts,[25] others instead identify the relevant detriment and then mould relief accordingly.[26] This will likely be a common point of contention in litigation given the latter approach increases the prospect that even a successful claimant will obtain a lesser award than fulfilment of the promise.
Many judgments prior to Kramer v Stone interpreted previous High Court decisions of Sidhu v Van Dyke[27] and Giumelli[28] as dictating that the “usual” or “prima facie” remedy for proprietary estoppel is fulfilment of the promise. Conversely, the Full Court of the Supreme Court of South Australia thought that the High Court decisions simply indicated that “in some cases, the appropriate relief will be the enforcement of the assumption or the expectation, while in other cases, the appropriate relief is something less, because to hold the defendant to the promise would be wholly disproportionate to the detriment suffered by the plaintiffs”.[29]
Kramer v Stone does not explicitly address the controversy. Rather, it distinguishes the approach to take between two extremes: compensation for a small monetary outlay and fulfilment of the promise for “life-changing decisions with irreversible consequences of a profoundly personal nature”.[30] This has left room for the divergence between authorities to continue.
Moreover, as the High Court’s direction to mould relief to prevent the detriment[31] bears at least a passing resemblance to the “minimum equity” principle,[32] litigants in at least one case have since argued that it again ought be applied in cases concerning property rights.[33] This rationale likely faces difficulty given most cases consider Giumelli rejected the principle[34] for cases of proprietary estoppel and Kramer v Stone’s approach to relief is in part based on that case.[35] There is however a real prospect that the High Court’s formulation means that the “minimum equity” principle no longer has a role to play in cases that do not involve property rights (i.e., promissory estoppel cases). It certainly seems like this could be the case given the approach in Kramer v Stone derives from proprietary estoppel cases.[36]
Impact: setting up rights other than in property
By formulating elements that encompasses both promissory and proprietary estoppel, another potential effect of Kramer v Stone is to enable estoppel claims to be advanced offensively even where the promise does not involve defined property rights (for example a promise to a share of an estate or the creation of a trust).
Certainly, since Kramer v Stone several cases have been run and decided without identifying the species of equitable estoppel, with one primary judge writing that “the result…did not turn on such distinctions”,[37] and in one other instance a claim framed as promissory estoppel was successful in setting up rights to certain property.[38]
Alternatively, given that the elements refine those expressed in Waltons Stores, previous commentary that the respective characteristics of promissory and proprietary estoppel continue to be relevant may still apply to prevent litigation of promissory estoppel claims in this way.
[1] [2024] HCA 48.
[2] Beyond confirming that no subsequent encouragement from a promise or actual knowledge of detrimental reliance is needed to establish such a claim.
[3] For the sake of brevity, in this article proprietary estoppel by encouragement will be referred to simply as “proprietary estoppel”, noting that this article is not intended to comment on the doctrine of proprietary estoppel by acquiescence.
[4] See DHJPM Pty Ltd v Blackthorn Resources Ltd [2011] NSWCA 348 (DHJPM), [43] – [44]; Douehi v Construction Technologies Australia Pty Ltd [2016] NSWCA 105 (Douehi), [166].
[5] Walton Stores (Interstate) Ltd v Maher [1988] HCA 7.
[6] See DHJPM, [43] – [44]; Douehi, [166]; Slade v Brose [20214] NSWCA 197, [200] – [201]; Federal Treasury Enterprise (FKP) Soujuzplodoimport v Spirits International BV [2024] FCAFC 152, [16].
[7] See Sullivan v Sullivan [2006] NSWCA 312, [85]; Kramer v Stone [2023] NSWCA 270, [84], [86] (Ward P), adopting Galaxidis v Galaxidis [2004] NSWCA 111, [93].
[8] Donis v Donis [2007] VSCA 89 (Donis), [19]; Delaforce v Simpson-Cook [2010] NSWCA 84, [63] – [65], Sidhu v Van Dyke [2014] HCA 19 (Sidhu), [82] – [86]; Commonwealth v Verwayen (1990) 170 CLR 394 (Verwayen), 443-445; Rowson v Alpass (No 2) [2024] VSC 169 (Rowson), [364] – [366].
[9] See Saleh v Romanous [2010] NSWCA 274, [55], [62], [74]; DHJPM, [47], [93]; Hammond v JP Morgan Trust Australia Ltd [2012] NSWCA 295, [26], Ashton v Pratt [2015] NSWCA 12, [138]; CPB Contractors Pty Ltd v Rizzani De Eccher Australia Pty Ltd [2017] NSWSC 1798, [340] – [342].
[10]See Crown Melbourne Ltd v Cosmopolitan Hotel (Vic) Pty Ltd [2016] HCA 26 (Crown Melbourne), [35] – [36] (French CJ, Kiefell and Bell JJ, who considered promissory estoppel required a clear and unequivocal promise but did not address the issue of contractual certainty or proprietary estoppel), [142] – [153] (Keane J, who considered a contractual level of certainty was required for promissory estoppel but not for proprietary estoppel), [210] – [211], [215] – [218] (Nettle J, who considered a promise of contractual certainty was not required but that the certainty requirements between promissory and proprietary estoppel ought be the same); Moore v Aubusson [2020] NSWSC 1466 (Moore v Aubusson), [354], [399] (Ward CJ in Eq).
[11] See Harris v Harris [2021] VSCA 138 (Harris), [64]; Rowson, [364] – [366]; ACN 074 971 109 Pty Ltd (atf the Argot Unit Trust) v National Mutual Life Association of Australasia Ltd [2008] VSCA 247 (Mutual Life), [169].
[12] See Q v E Co [2020] NSWCA 220, [71] – [86].
[13] Hart v Basha [2024] NSWSC 1441; Lucas v Salman [2022] NSWSC 1301; Antov v Bokan [2018] NSWSC 1474. Cf Quinn v Bryant [2011] NSWSC 1153, affirmed in Quinn v Bryant [2012] NSWCA 377 which succeeded as an “equitable estoppel” claim without reference to the principles of proprietary or promissory estoppel.
[14] Moore v Aubusson; Bull v Bull [2024] SADC 109. See also the obiter discussion in Varma v Varma [2010] NSWSC 786, [490] – [491].
[15] Kramer v Stone, [40].
[16] Kramer v Stone, [40].
[17] See footnote 8 above.
[18] See for example Galatidis v Kallidis [2025] NSWSC 1555, [71] – [72]; Hyde v Hyde & Ors [2026] SASCA 13, [94] – [98]; Penya v Penya [2026] NSWCA 73 (Penya), [37] – [40], [75]; Bruce v Bruce [2026] NSWSC 900, [243]; Wright v Kennedy [2026] NSWSC 834, [315] – [316]; McFarlane v McFarlane [2026] NSWSC 772, [22] – [24]; Silk v Silk [2026] VSCA 152, [111], [187] – [190]; Tsamakis v Tsamakis [2026] VSC 386 (Tsamakis), [57] – [59]. Cf MBP Properties Pty Ltd v Barnes [2026] WASC 276, 349], doubt expressed in obiter in Kronenberg v Macaulay [2025] NSWCA 195, [151] – [154], [158] – [160]; Bahnik v Budimir [2025] NSWSC 1595 , [35]; Penya, [38], [75].
[19] Legione v Hateley (1983) 46 ALR 1 (Legione v Hateley), 22.
[20] Crown Melbourne, [35].
[21] Legione v Hateley, 23-24.
[22] Ibid.
[23] Ibid.
[24] See the discussion in Les & Zelda Investments Pty Ltd atf Les & Zelda Family Trust v Whitehaven Coal Ltd (No 4) [2026] NSWSC 107, [1338] – [1344].
[25] See Bahnik v Budimir (No 2) [2026] NSWSC 456, [8] – [15]; Milenkovic v Milenkovic [2026] VSCA 151, [145], [153]; Mills v Dodds [2025] NSWSC 396, [582] – [586].
[26] TJ & P Pty Ltd as trustee for the Post Family Trust v Agrinova Pty Ltd [2026] FCAFC 77 (Agrinova), [333] – [338]; Tsamakis, [67] – [69].
[27] [2014] HCA 19.
[28] Giumelli v Giumelli [1999] HCA 10 (Giumelli).
[29] Commercial & General Corporation Pty Ltd v Manassen Holdings Pty Ltd [2021] SASCFC 40, [154] – [156].
[30] Agrinova, [114].
[31] Kramer v Stone [40].
[32] This principle dictates relief be “no more than necessary to avoid detriment”: Mutual Life, [166] – [171].
[33] Saad v Saad [2025] VSCA 29, [23] (argued but not decided).
[34] Giumelli at [48], [63]. See discussion on minimum equity in Mills v Dodds, [582] – [590] and Harris, [64] – [79]. Cf Mutual Life, [169].
[35] Kramer v Stone, [40].
[36] See Pipikos v Trayans [2018] HCA 39, Sidhu, Donis and Verwayen. Cf the approach taken post-Kramer in Mills v Dodds, [582] – [590], but which does not reference the case (it appears to have been argued prior to the High Court’s decision).
[37] TJ & P Pty Ltd atf Post Family Trust v Agrinova Pty Ltd (No 3) [2025] FCA 587, [269]. See also Perez de la Sala v Perez de la Sala (No 4) [2026] NSWSC 163, [277] – [278] and Tsamakis, [53] – [55].
[38] Whittorn v Siu [2026] NSWSC 666.
